Cubic Feet Per Minute To Cubic Metres Per Second Converter

Formula

The conversion factor is small because a minute has 60 seconds. Keep enough decimals in m3/s if the value will be used in later calculations.

Engineering Notes

m3/s is useful in equations, but it can be awkward in everyday product discussion. A value such as 0.0472 m3/s may be more readable as 47.2 L/s. The tool shows both so you can choose the unit that fits the schedule. In design notes, keep one unit per column and state whether values are design, catalogue, measured or corrected values.

If temperature or pressure differs from the reference condition used by an instrument, a volume flow reading may need correction before a mass flow calculation. This page only changes units after the volume flow value has been chosen.

Velocity And Area Notes

The optional velocity line is a simple average: flow divided by area. It is useful for first-pass duct checks and opening checks, but it does not describe every point across the duct. Real velocity profiles are affected by bends, dampers, grilles, fans, filters and how far the measurement point is from a disturbance. If a design requires a measured velocity, use a proper instrument and the measurement method specified for the project.

Area should be the free area available for air, not always the outside size. A grille, louvre or perforated panel can have a free area much smaller than its frame. A circular duct area is pi times radius squared, while a rectangular duct area is width times height. Put the same area basis in every calculation so the velocity line is meaningful.

Choosing Between L/s And m3/s

For small room ventilation, litres per second may be easier to read because values are usually tens or hundreds. For larger plant, m3/s keeps numbers compact and aligns with SI equations. A schedule can show both, but the project should choose one controlling unit. If a contractor prices from CFM data and the engineer checks m3/s data, keep the converted value and factor in the notes so the comparison can be audited later.

Using The Result In A Calculation

When the converted m3/s value is used for heat, contaminant or velocity calculations, keep the same time base throughout the worksheet. Do not mix m3/s in one row with m3/h in another unless each row is clearly labelled. If a formula uses air density, the next step may need kg/s rather than m3/s, and that requires density information. This page stops at volume flow so it does not hide those assumptions.

For tender documents, include the conversion factor in a note. A reviewer can then trace a CFM catalogue value back to the SI figure without guessing which rounded factor was used.

Common Mistakes To Avoid

• Using the m3/h factor when the formula needs m3/s.
• Dropping leading zeros in small m3/s values.
• Rounding m3/s too early before a velocity calculation.
• Using nominal duct size instead of actual free area.
• Adding flows that are not operating at the same time.